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View Full Version : Problem using QPainter for overlaying in QOpenGLWidget



demidemi1125
03-08-2015, 09:54 PM
Hi, every one.
I've received the problem, using QPainter for overlaying in QOpenGLWidget Qt.

I create a 'CameraSurface_GL' class that draw yuv image received from ip camera.
Here's my code.


#include "camerasurface_gl.h"
#include <QtWidgets>
#include <QtGui>
#include <QOpenGLFunctions_3_0>

const char* YUV420P_VS = ""
"#version 330\n"
""
"uniform mat4 u_pm;"
"uniform vec4 draw_pos;"
""
"const vec2 verts[4] = vec2[] ("
" vec2(-0.5, 0.5), "
" vec2(-0.5, -0.5), "
" vec2( 0.5, 0.5), "
" vec2( 0.5, -0.5) "
");"
""
"const vec2 texcoords[4] = vec2[] ("
" vec2(0.0, 1.0), "
" vec2(0.0, 0.0), "
" vec2(1.0, 1.0), "
" vec2(1.0, 0.0) "
"); "
""
"out vec2 v_coord; "
""
"void main() {"
" vec2 vert = verts[gl_VertexID];"
" vec4 p = vec4((0.5 * draw_pos.z) + draw_pos.x + (vert.x * draw_pos.z), "
" (0.5 * draw_pos.w) + draw_pos.y + (vert.y * draw_pos.w), "
" 0, 1);"
" gl_Position = u_pm * p;"
" v_coord = texcoords[gl_VertexID];"
"}"
"";

const char* YUV420P_FS = ""
"#version 330\n"
"uniform sampler2D y_tex;"
"uniform sampler2D u_tex;"
"uniform sampler2D v_tex;"
"in vec2 v_coord;"
"layout( location = 0 ) out vec4 fragcolor;"
""
"const vec3 R_cf = vec3(1, 0.000000, 1.13983);"
"const vec3 G_cf = vec3(1, -0.39465, -0.58060);"
"const vec3 B_cf = vec3(1, 2.03211, 0.000000);"
"const vec3 offset = vec3(-0.0625, -0.5, -0.5);"
""
"void main() {"
" float y = texture(y_tex, v_coord).r;"
" float u = texture(u_tex, v_coord).r;"
" float v = texture(v_tex, v_coord).r;"
" vec3 yuv = vec3(y,u,v);"
" yuv += offset;"
" fragcolor = vec4(0.0, 0.0, 0.0, 1.0);"
" fragcolor.r = dot(yuv, R_cf);"
" fragcolor.g = dot(yuv, G_cf);"
" fragcolor.b = dot(yuv, B_cf);"
"}"
"";


CameraSurface_GL::CameraSurface_GL(QWidget *parent) :
QOpenGLWidget(parent)
,vid_w(0)
,vid_h(0)
,win_w(0)
,win_h(0)
,vao(0)
,vao1(0)
,y_tex(0)
,u_tex(0)
,v_tex(0)
,vert(0)
,frag(0)
,prog(0)
,u_pos(-1)
,textures_created(false)
,shader_created(false)
{
qRegisterMetaType<YUVFrame>("YUVFrame");
m_ipCamera = new IpCamera;

m_yuvWidth = 0;
m_yuvHeight = 0;


connect(m_ipCamera, SIGNAL(frameChanged(YUVFrame)), this, SLOT(slotFrameChanged(YUVFrame)));

m_frameCount = 0;
m_setup = 0;
}

CameraSurface_GL::~CameraSurface_GL()
{
glDeleteTextures(1, &y_tex);
glDeleteTextures(1, &u_tex);
glDeleteTextures(1, &v_tex);

glDeleteProgram(prog);
}

void CameraSurface_GL::openCamera(QString ipAddress, QString userName, QString password)
{
if(m_ipCamera->isRunning())
m_ipCamera->close();

qDebug() << "open camera";

bool opend = m_ipCamera->open(ipAddress, userName, password);
if(opend == false)
return;
}

void CameraSurface_GL::closeCamera()
{
m_ipCamera->close();
}

void CameraSurface_GL::slotFrameChanged(YUVFrame frame)
{
m_yuvData = QByteArray((char*)frame.yuvData, frame.width * frame.height * 3 / 2);
m_yuvWidth = frame.width;
m_yuvHeight = frame.height;

if(m_setup == 0)
{
setup_gl(frame.width, frame.height);
resize_gl(rect().width(), rect().height());

m_setup = 1;
}

update();

m_frameCount ++;
}

void CameraSurface_GL::setup_gl(int width, int height)
{
vid_w = width;
vid_h = height;

if(!vid_w || !vid_h) {
printf("Invalid texture size.\n");
return;
}

if(!setupTextures()) {
return;
}

if(!setupShader()) {
return;
}

return;
}

void CameraSurface_GL::resize_gl(int width, int height)
{
win_w = width;
win_h = height;

pm.setToIdentity();
pm.ortho(0, win_w, win_h, 0, 0.0, 100.0f);

glUseProgram(prog);
glUniformMatrix4fv(glGetUniformLocation(prog, "u_pm"), 1, GL_FALSE, pm.data());
}

void CameraSurface_GL::resizeGL(int width, int height)
{
glViewport(0, 0, width, height);
if(m_setup)
{
resize_gl(width, height);
}
}

bool CameraSurface_GL::setupTextures()
{
if(textures_created) {
printf("Textures already created.\n");
return false;
}

glGenTextures(1, &y_tex);
glBindTexture(GL_TEXTURE_2D, y_tex);
glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, vid_w, vid_h, 0, GL_RED, GL_UNSIGNED_BYTE, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

glGenTextures(1, &u_tex);
glBindTexture(GL_TEXTURE_2D, u_tex);
glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, vid_w/2, vid_h/2, 0, GL_RED, GL_UNSIGNED_BYTE, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

glGenTextures(1, &v_tex);
glBindTexture(GL_TEXTURE_2D, v_tex);
glTexImage2D(GL_TEXTURE_2D, 0, GL_R8, vid_w/2, vid_h/2, 0, GL_RED, GL_UNSIGNED_BYTE, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

textures_created = true;

return true;
}

bool CameraSurface_GL::setupShader()
{
if(shader_created) {
printf("Already creatd the shader.\n");
return false;
}

vert = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vert, 1, &YUV420P_VS, 0);
glCompileShader(vert);

frag = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(frag, 1, &YUV420P_FS, 0);
glCompileShader(frag);

prog = glCreateProgram();
glAttachShader(prog, vert);
glAttachShader(prog, frag);
glLinkProgram(prog);

glUseProgram(prog);
glUniform1i(glGetUniformLocation(prog, "y_tex"), 0);
glUniform1i(glGetUniformLocation(prog, "u_tex"), 1);
glUniform1i(glGetUniformLocation(prog, "v_tex"), 2);

u_pos = glGetUniformLocation(prog, "draw_pos");

glUseProgram(0);

return true;
}

void CameraSurface_GL::setYPixels(uint8_t* pixels, int stride)
{
glBindTexture(GL_TEXTURE_2D, y_tex);
glPixelStorei(GL_UNPACK_ROW_LENGTH, stride);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, vid_w, vid_h, GL_RED, GL_UNSIGNED_BYTE, pixels);
}

void CameraSurface_GL::setUPixels(uint8_t* pixels, int stride)
{
glBindTexture(GL_TEXTURE_2D, u_tex);
glPixelStorei(GL_UNPACK_ROW_LENGTH, stride);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, vid_w/2, vid_h/2, GL_RED, GL_UNSIGNED_BYTE, pixels);
}

void CameraSurface_GL::setVPixels(uint8_t* pixels, int stride)
{
glBindTexture(GL_TEXTURE_2D, v_tex);
glPixelStorei(GL_UNPACK_ROW_LENGTH, stride);
glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, vid_w/2, vid_h/2, GL_RED, GL_UNSIGNED_BYTE, pixels);
}


void CameraSurface_GL::initializeGL()
{
initializeOpenGLFunctions();
glClearColor(0, 0, 0, 1);
}

void CameraSurface_GL::paintEvent(QPaintEvent* e)
{
QPainter painter;
painter.begin(this);

painter.beginNativePainting();

glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

if(m_yuvData.size())
{
setYPixels((unsigned char*)m_yuvData.data(), m_yuvWidth);
setUPixels((unsigned char*)m_yuvData.data() + m_yuvWidth * m_yuvHeight, m_yuvWidth / 2);
setVPixels((unsigned char*)m_yuvData.data() + m_yuvWidth * m_yuvHeight * 5 / 4, m_yuvWidth / 2);

glBindVertexArray(vao);
glUseProgram(prog);

glUniform4f(u_pos, rect().left(), rect().top(), rect().width(), rect().height());

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, y_tex);

glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, u_tex);

glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, v_tex);

glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

glUseProgram(0);
}

painter.endNativePainting();

painter.end();
}


I want to the draw contents on the yuv layer, so I appended the following code in 'void paintEvent(QPaintEvent* e)' functions.




void CameraSurface_GL::paintEvent(QPaintEvent* e)
{
QPainter painter;
painter.begin(this);

painter.beginNativePainting();

glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

if(m_yuvData.size())
{
setYPixels((unsigned char*)m_yuvData.data(), m_yuvWidth);
setUPixels((unsigned char*)m_yuvData.data() + m_yuvWidth * m_yuvHeight, m_yuvWidth / 2);
setVPixels((unsigned char*)m_yuvData.data() + m_yuvWidth * m_yuvHeight * 5 / 4, m_yuvWidth / 2);

glBindVertexArray(vao);
glUseProgram(prog);

glUniform4f(u_pos, rect().left(), rect().top(), rect().width(), rect().height());

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, y_tex);

glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, u_tex);

glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, v_tex);

glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

glUseProgram(0);
}

painter.endNativePainting();

//////new appended code//////
QPixmap memPix(rect().width(), rect().height());
QPainter memDC;
memDC.setPen(Qt::red);
memDC.drawRect(QRect(0, 0, 100, 100));

painter.drawPixmap(rect(), memPix);

/////end/////


painter.end();
}


At this time, I received the issue crashing my program.

And, When I also changed to the following, I received the same.




void CameraSurface_GL::paintEvent(QPaintEvent* e)
{
QPainter painter;
painter.begin(this);

painter.beginNativePainting();

glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

if(m_yuvData.size())
{
setYPixels((unsigned char*)m_yuvData.data(), m_yuvWidth);
setUPixels((unsigned char*)m_yuvData.data() + m_yuvWidth * m_yuvHeight, m_yuvWidth / 2);
setVPixels((unsigned char*)m_yuvData.data() + m_yuvWidth * m_yuvHeight * 5 / 4, m_yuvWidth / 2);
}

painter.endNativePainting();

QPixmap memPix(rect().width(), rect().height());
QPainter memDC;
memDC.setPen(Qt::red);
memDC.drawRect(QRect(0, 0, 100, 100));

painter.drawPixmap(rect(), memPix);
painter.end();
}


And, When I remove the part of calling 'setYPixels', 'setUPixels' and 'setVPixels', my program is not crashing.

I can't know why I received the error. I want to know the cause of this issue.
Help me, Thanks.